The Poppy War Books in Order

When orphaned war survivor Rin aces the Keju—the Empire-wide test to find the most talented youth—no one is more surprised than she is. Escaping a life of servitude and despair, she's earned her place at Sinegard, the most elite military school in Nikan.

But being a dark-skinned peasant girl from the south makes her an outcast among the privileged scions of wealth and power. Targeted by rival classmates for her color, poverty, and gender, Rin discovers she possesses a lethal, unearthly power—an aptitude for the nearly-mythical art of shamanism.

Under the tutelage of a seemingly insane teacher and through dangerous experiments with psychoactive substances, Rin learns that the gods long thought dead are very much alive—and she might be able to wield their power.

As the threat of a Third Poppy War looms, Rin's shamanic abilities may be the only hope for her people. But invoking the vengeful Phoenix god could cost her not just her humanity, but perhaps her very soul...